In order to most efficiently apply force to the pedal of a bicycle, it is necessary to attach the rider's foot securely so that, in addition to applying force over the downward portion of the pedal stroke, the rider can pull up and back over the other portions of the circle described by the pedal.
Until the early 1980s, there was in common use only one method of securely attaching a bicycle rider's foot to a bicycle pedal: toe clips and straps combined with cleated shoes. In general terms, this system consists of two parts. The first is a cleat bolted to the bottom of a cycling shoe through slotted holes in the cleat allowing varying degrees of static fore-and aft and rotational adjustment, and which includes a deep narrow groove on its lower surface. This groove mates to a vertical metal plate attached to the pedal which, like the groove, is perpendicular to the long dimension of the foot. The second part of the system consists of a metal or plastic clip which attaches at one end to the front of the pedal, wraps around the front and top of the shoe and terminates in one or two loops through which a strap may pass. The toe strap wraps around the foot and through both the loop(s) at the end of the clip and through the pedal itself. The strap is secured and adjusted in tension by means of a spring-tensioned adjuster at one end.
The traditional toe clips and straps are fairly effective in accomplishing the purpose of attaching the rider's foot to the pedal: the cleat securely positions the shoe relative to the pedal in the fore-and-aft plane, while the strap secures the foot relative to the pedal in the vertical and side-to-side planes. Many traditional pedals have the added advantage of allowing casual use with uncleated shoes, although with reduced efficiency. However, the traditional system has several shortcomings. First, the foot cannot be removed from the pedal without loosening the toe strap, which requires the rider to reach down with a hand, which is inconvenient at best and often dangerous. Second, it does not provide for reliable release in the event of an emergency or crash. Third, the raised cleat, which is generally made of hard plastic, makes the shoe difficult and somewhat dangerous to walk in. Fourth, the traditional pedal is topheavy, and therefore hangs upside down prior to entry, making entry difficult, particularly in situations such as starting from rest while travelling uphill. Finally, the cleat tends to clog with mud and dirt, making use of cleated shoes highly impractical for mountain bikes.
Various systems have been designed and introduced over the past years in an attempt to overcome many, if not all, of the foregoing difficulties. For example, many years ago, a "uniblock" system was introduced that consisted of a cleat with a cylindrical hole; the cleat fitting into a recessed channel provided in the pedal. When appropriately positioned, the hole in the cleat lined up with the pin in the pedal which the rider could force through the hole by hand; the cleat and pedal were locked and unlocked from one another by hand. Not only did this system not provide for a hands free release, it also tended to clog with dirt and mud especially if used off road, and the raised cleat made walking difficult. In addition this system did not provide for dynamic rotational adjustment.
More recently, a "Look" system was introduced which appears to incorporate certain ski binding devices and technology. The Look system provides a cleat bolted to the bicyclist's shoe which is set in a spring loaded mechanism provided on the pedal by setting the toe end of the cleat under a lip on the pedal then rocking the shoe back relative to the pedal to snap the rear end of the cleat into the spring loaded mechanism. While this system permits a hands free release of the shoe from the pedal, the raised cleat makes walking in the shoe impractical. Also the mechanism tends to clog easily with dirt, and the contour and size of the pedal make the pedal difficult to use unless the cleat is fully engaged. Also, the pedal does not present a surface that is compatible with street shoes.
In more recent times, several other "clipless" systems have been offered to bicyclists. Included among them is the "Cyclebinding," system (which in general reversed the Look system, placing a recess in the sole of the shoe and a protruding spring-loaded mechanism on the pedal designed to fit into the recess), the Vortechs system (which provides a cleat with a protruding peg on the shoe, the peg fitting into a hole provided in the pedal) and the "Time" system (which is much like the Look system). Other recent systems have been developed and offered by Sampson, Campaganolo, Aerolite, Adidas, Keywin and MK.
While each of these systems overcome some difficulties and provides some advantages over the traditional bicycle pedal, all but the Cyclebinding comprise a male component attached to the shoe which interfits with a female component attached to the pedal. The raised male component makes walking difficult, while the female component makes the pedal incompatible with street shoes. Of particular concern for mountain bicycling, the male-female interfit is easily rendered inoperable by dirt in all of these system, including the Cyclebinding. Thus, currently there is no truly effective system on the market for attaching a bicycle shoe to a pedal.
Ideally, a system for attaching a shoe to a bicycle pedal should be unaffected by dirt and mud, allow easy and safe hands free entry and exit, release automatically in the event of a crash or other emergency, provide a flat, safe walking surface on the shoe, permit use of the pedal (and bike) with normal shoes, allow effective use of the pedal in situations in which engagement of the mechanism is not yet completed, or proves difficult or undesirable, allow both static and dynamic rotational adjustment of the shoe relative to the pedal, be lightweight, and permit easy disassembly and replacement of worn or stressed parts.
These and other objects of the present invention will be apparent to those skilled in this field from the following detailed description of a preferred embodiment of the present invention.